Repeated presentations of sensory stimuli generate transient gamma-frequency (30-80 Hz) responses in neocortex that show plasticity in a task-dependent manner. Complex relationships between individual neuronal outputs and the mean, local field potential (population activity) accompany these changes, but little is known about the underlying mechanisms responsible. Here we show that transient stimulation of input layer 4 sufficient to generate gamma oscillations induced two different, lamina-specific plastic processes that correlated with lamina-specific changes in responses to further, repeated stimulation: Unit rates and recruitment showed overall enhancement in supragranular layers and suppression in infragranular layers associated with excitatory or inhibitory synaptic potentiation onto principal cells, respectively. Both synaptic processes were critically dependent on activation of GABAB receptors and, together, appeared to temporally segregate the cortical representation. These data suggest that adaptation to repetitive sensory input dramatically alters the spatiotemporal properties of the neocortical response in a manner that may both refine and minimize cortical output simultaneously.
Proc Natl Acad Sci U S A
E2721 - E2729
GABAB receptor, gamma rhythms, habituation, sensory processing, synaptic plasticity, Action Potentials, Animals, Cells, Cultured, Electric Stimulation, GABAergic Neurons, Gamma Rhythm, Neocortex, Nerve Net, Neuronal Plasticity, Rats, Rats, Wistar, Receptors, GABA-B, Synaptic Transmission